Maintenance and Service 8-23
Problem Description Problems/Suggestions
Flooded instrument Butanol liquid is present in the
instrument optics causing a
variety of problems including
erratic or very low
concentration readings,
changes in aerosol flow rate,
and/or changes in transducer
pressure measurements.
Although the 3775 CPC has been designed to resist
flooding, it can occur if the instrument is shipped
without properly drying or removing a wet wick.
Flooding can also occur if the inlet is blocked or the
instrument is tipped during operation.
Once the instrument cover is removed, evidence of
flooding is seen by examining air tubing for the
presence of liquid. Start by looking at tubing
downstream of an optics. Carefully remove and dry
out wet tubing then replace. Note, don’t dry the
tubing in place to avoid damaging other parts in the
CPC.
If flooding has occurred, it will be necessary to dry
the optics block.* Begin by draining the butanol and
removing the wick as described earlier. Replace the
reservoir cover without replacing the wick. Turn the
instrument on and make sure the pump is on. Allow
the instrument to operate for at least 24 hours.
Status: Laser power
low
Detector in the laser indicates
low laser power.
Contact a TSI service technician.
Status: Liquid level
low
Liquid level sensor in the
reservoir does not detect the
presence of butanol.
Verify that no liquid is present in the reservoir by
looking through the clear reservoir cover. If no liquid
level line is seen, check carefully to confirm that it is
not overfilled, indicating a problem in the butanol
level detection circuitry.
Add butanol to the fill bottle and connect the bottle
at the quick connect fitting.
Make sure the Auto Fill Enable is selected ON in the
User Settings menu (
Figure 4-5).
Watch the reservoir to confirm that it fills then
stops. If filling does not occur, the fill filter may need
to be replaced. Refer to “
Changing the Filters”
presented earlier.
*Flooding can contaminate the lens surfaces in the optics block reducing signal strength and instrument
sensitivity. Lens cleaning is performed at the factory if flooding occurs. A noticeable change in instrument
performance characteristics (e.g., lowered detected concentration) can indicate the need to return the
instrument to TSI for maintenance.
Calibrating and Entering New Orifice Flow
Data
A stable “volumetric” flow through the sensor is maintained using a
saphire orifice operating at a cirtical pressure drop. The orifice
fitting is threaded into the optics block as shown in
Figure 8-11.
Stable critical flow through the orifice is achieved using a high
vacuum diaphram pump. For more information on critical pressure
and flow refer to
Chapter 5.
The nominal aerosol flow is 0.3 L/min. The critical orifice for
aerosol flow is calibrated at the factory and the actual flow is
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